The Wiki's page about Hocotatians mention that they eyes are
closed most of the time, but, in fact, they aren't closed, they are
just flattened, an the pupil is as big as the entierly eye.

Here's a gif to show you what I mean:

Also, the finale cutscene (at 1:29 on the video), of the game
show very closely the eyes of Olimar during their "transformation",
and we can see there's still a little bit of white surrounding the
pupil in the "neutral stade":